This invention relates to an apparatus to prevent overcurrent or overvoltage by disconnecting a load from a power source.
More particularly, this invention concerns an apparatus to prevent overcurrent to the load or overvoltage of the power source, by employing a semiconductor negative resistance device which comprises a complementary connection of a pair of FETs.
In electric appliances, in order to prevent overcurrent of the appliance, generally a fuse has been employed. In such an arrangement, when an accidental trouble such as overvoltage in the power source or a short circuit in the load causes overcurrent in the load, the fuse breaks to disconnect the load from the power source. Though the fuse is very popular and cheap, in order to break, a considerable increase of current is required, and therefore it is not sensitive to a moderate overcurrent. Moveover, whenever a fuse is broken by an overcurrent, it is always necessary to replace it with another fuse in order to restore the operation of the appliance, and the replacement is troublesome work. Though other overcurrent prevention means, such as electromagnetic systems and thermal-operation systems have been employed previously, these are neither compact not economical.